Solution
 

I had the exact error come up in RHEL4 WS. The kernel module compiled but would not install correctly even if I manually installed the module. I looked at the script (install.sh) that installs the module and found the problem. First of all, I su to root to build and install the module. By default, /sbin is not in the path. Because of this, when the script tries to do an lsmod it fails to find the lsmod executable and instead of giving a decent message about that, it dumps out the

'An error has occurred during the check process which prevented the installation from completing. It's not possible to build a standalone driver on this host. The kernel don't export a neccesary symbols for the device driver and we aren't able to load the driver. Please compile the kernel and the driver manually.'

message. If you edit the line:

insmod_count='lsmod | grep $drv_name -c'

(it was line 1234 in the version I used) and change it to

insmod_count='/sbin/lsmod | grep $drv_name -c'

then the driver will properly install.